diff options
Diffstat (limited to 'fs/debugfs')
| -rw-r--r-- | fs/debugfs/Makefile | 1 | ||||
| -rw-r--r-- | fs/debugfs/file.c | 823 | ||||
| -rw-r--r-- | fs/debugfs/inode.c | 841 | ||||
| -rw-r--r-- | fs/debugfs/internal.h | 46 |
4 files changed, 1035 insertions, 676 deletions
diff --git a/fs/debugfs/Makefile b/fs/debugfs/Makefile index 840c45696668..9c0fe38cfb5e 100644 --- a/fs/debugfs/Makefile +++ b/fs/debugfs/Makefile @@ -1,3 +1,4 @@ +# SPDX-License-Identifier: GPL-2.0-only debugfs-objs := inode.o file.o obj-$(CONFIG_DEBUG_FS) += debugfs.o diff --git a/fs/debugfs/file.c b/fs/debugfs/file.c index 4fce1da7db23..3ec3324c2060 100644 --- a/fs/debugfs/file.c +++ b/fs/debugfs/file.c @@ -18,7 +18,9 @@ #include <linux/slab.h> #include <linux/atomic.h> #include <linux/device.h> +#include <linux/pm_runtime.h> #include <linux/poll.h> +#include <linux/security.h> #include "internal.h" @@ -45,58 +47,81 @@ const struct file_operations debugfs_noop_file_operations = { #define F_DENTRY(filp) ((filp)->f_path.dentry) -const struct file_operations *debugfs_real_fops(const struct file *filp) +void *debugfs_get_aux(const struct file *file) { - struct debugfs_fsdata *fsd = F_DENTRY(filp)->d_fsdata; - - if ((unsigned long)fsd & DEBUGFS_FSDATA_IS_REAL_FOPS_BIT) { - /* - * Urgh, we've been called w/o a protecting - * debugfs_file_get(). - */ - WARN_ON(1); - return NULL; - } - - return fsd->real_fops; + return DEBUGFS_I(file_inode(file))->aux; } -EXPORT_SYMBOL_GPL(debugfs_real_fops); +EXPORT_SYMBOL_GPL(debugfs_get_aux); -/** - * debugfs_file_get - mark the beginning of file data access - * @dentry: the dentry object whose data is being accessed. - * - * Up to a matching call to debugfs_file_put(), any successive call - * into the file removing functions debugfs_remove() and - * debugfs_remove_recursive() will block. Since associated private - * file data may only get freed after a successful return of any of - * the removal functions, you may safely access it after a successful - * call to debugfs_file_get() without worrying about lifetime issues. - * - * If -%EIO is returned, the file has already been removed and thus, - * it is not safe to access any of its data. If, on the other hand, - * it is allowed to access the file data, zero is returned. - */ -int debugfs_file_get(struct dentry *dentry) +enum dbgfs_get_mode { + DBGFS_GET_ALREADY, + DBGFS_GET_REGULAR, + DBGFS_GET_SHORT, +}; + +static int __debugfs_file_get(struct dentry *dentry, enum dbgfs_get_mode mode) { struct debugfs_fsdata *fsd; void *d_fsd; + /* + * This could only happen if some debugfs user erroneously calls + * debugfs_file_get() on a dentry that isn't even a file, let + * them know about it. + */ + if (WARN_ON(!d_is_reg(dentry))) + return -EINVAL; + d_fsd = READ_ONCE(dentry->d_fsdata); - if (!((unsigned long)d_fsd & DEBUGFS_FSDATA_IS_REAL_FOPS_BIT)) { + if (d_fsd) { fsd = d_fsd; } else { + struct inode *inode = dentry->d_inode; + unsigned int methods = 0; + + if (WARN_ON(mode == DBGFS_GET_ALREADY)) + return -EINVAL; + fsd = kmalloc(sizeof(*fsd), GFP_KERNEL); if (!fsd) return -ENOMEM; - fsd->real_fops = (void *)((unsigned long)d_fsd & - ~DEBUGFS_FSDATA_IS_REAL_FOPS_BIT); + if (mode == DBGFS_GET_SHORT) { + const struct debugfs_short_fops *ops; + ops = fsd->short_fops = DEBUGFS_I(inode)->short_fops; + if (ops->llseek) + methods |= HAS_LSEEK; + if (ops->read) + methods |= HAS_READ; + if (ops->write) + methods |= HAS_WRITE; + fsd->real_fops = NULL; + } else { + const struct file_operations *ops; + ops = fsd->real_fops = DEBUGFS_I(inode)->real_fops; + if (ops->llseek) + methods |= HAS_LSEEK; + if (ops->read) + methods |= HAS_READ; + if (ops->write) + methods |= HAS_WRITE; + if (ops->unlocked_ioctl) + methods |= HAS_IOCTL; + if (ops->poll) + methods |= HAS_POLL; + fsd->short_fops = NULL; + } + fsd->methods = methods; refcount_set(&fsd->active_users, 1); init_completion(&fsd->active_users_drained); - if (cmpxchg(&dentry->d_fsdata, d_fsd, fsd) != d_fsd) { + INIT_LIST_HEAD(&fsd->cancellations); + mutex_init(&fsd->cancellations_mtx); + + d_fsd = cmpxchg(&dentry->d_fsdata, NULL, fsd); + if (d_fsd) { + mutex_destroy(&fsd->cancellations_mtx); kfree(fsd); - fsd = READ_ONCE(dentry->d_fsdata); + fsd = d_fsd; } } @@ -116,6 +141,26 @@ int debugfs_file_get(struct dentry *dentry) return 0; } + +/** + * debugfs_file_get - mark the beginning of file data access + * @dentry: the dentry object whose data is being accessed. + * + * Up to a matching call to debugfs_file_put(), any successive call + * into the file removing functions debugfs_remove() and + * debugfs_remove_recursive() will block. Since associated private + * file data may only get freed after a successful return of any of + * the removal functions, you may safely access it after a successful + * call to debugfs_file_get() without worrying about lifetime issues. + * + * If -%EIO is returned, the file has already been removed and thus, + * it is not safe to access any of its data. If, on the other hand, + * it is allowed to access the file data, zero is returned. + */ +int debugfs_file_get(struct dentry *dentry) +{ + return __debugfs_file_get(dentry, DBGFS_GET_ALREADY); +} EXPORT_SYMBOL_GPL(debugfs_file_get); /** @@ -136,19 +181,130 @@ void debugfs_file_put(struct dentry *dentry) } EXPORT_SYMBOL_GPL(debugfs_file_put); +/** + * debugfs_enter_cancellation - enter a debugfs cancellation + * @file: the file being accessed + * @cancellation: the cancellation object, the cancel callback + * inside of it must be initialized + * + * When a debugfs file is removed it needs to wait for all active + * operations to complete. However, the operation itself may need + * to wait for hardware or completion of some asynchronous process + * or similar. As such, it may need to be cancelled to avoid long + * waits or even deadlocks. + * + * This function can be used inside a debugfs handler that may + * need to be cancelled. As soon as this function is called, the + * cancellation's 'cancel' callback may be called, at which point + * the caller should proceed to call debugfs_leave_cancellation() + * and leave the debugfs handler function as soon as possible. + * Note that the 'cancel' callback is only ever called in the + * context of some kind of debugfs_remove(). + * + * This function must be paired with debugfs_leave_cancellation(). + */ +void debugfs_enter_cancellation(struct file *file, + struct debugfs_cancellation *cancellation) +{ + struct debugfs_fsdata *fsd; + struct dentry *dentry = F_DENTRY(file); + + INIT_LIST_HEAD(&cancellation->list); + + if (WARN_ON(!d_is_reg(dentry))) + return; + + if (WARN_ON(!cancellation->cancel)) + return; + + fsd = READ_ONCE(dentry->d_fsdata); + if (WARN_ON(!fsd)) + return; + + mutex_lock(&fsd->cancellations_mtx); + list_add(&cancellation->list, &fsd->cancellations); + mutex_unlock(&fsd->cancellations_mtx); + + /* if we're already removing wake it up to cancel */ + if (d_unlinked(dentry)) + complete(&fsd->active_users_drained); +} +EXPORT_SYMBOL_GPL(debugfs_enter_cancellation); + +/** + * debugfs_leave_cancellation - leave cancellation section + * @file: the file being accessed + * @cancellation: the cancellation previously registered with + * debugfs_enter_cancellation() + * + * See the documentation of debugfs_enter_cancellation(). + */ +void debugfs_leave_cancellation(struct file *file, + struct debugfs_cancellation *cancellation) +{ + struct debugfs_fsdata *fsd; + struct dentry *dentry = F_DENTRY(file); + + if (WARN_ON(!d_is_reg(dentry))) + return; + + fsd = READ_ONCE(dentry->d_fsdata); + if (WARN_ON(!fsd)) + return; + + mutex_lock(&fsd->cancellations_mtx); + if (!list_empty(&cancellation->list)) + list_del(&cancellation->list); + mutex_unlock(&fsd->cancellations_mtx); +} +EXPORT_SYMBOL_GPL(debugfs_leave_cancellation); + +/* + * Only permit access to world-readable files when the kernel is locked down. + * We also need to exclude any file that has ways to write or alter it as root + * can bypass the permissions check. + */ +static int debugfs_locked_down(struct inode *inode, + struct file *filp, + const struct file_operations *real_fops) +{ + if ((inode->i_mode & 07777 & ~0444) == 0 && + !(filp->f_mode & FMODE_WRITE) && + (!real_fops || + (!real_fops->unlocked_ioctl && + !real_fops->compat_ioctl && + !real_fops->mmap))) + return 0; + + if (security_locked_down(LOCKDOWN_DEBUGFS)) + return -EPERM; + + return 0; +} + static int open_proxy_open(struct inode *inode, struct file *filp) { struct dentry *dentry = F_DENTRY(filp); - const struct file_operations *real_fops = NULL; + const struct file_operations *real_fops = DEBUGFS_I(inode)->real_fops; int r; - r = debugfs_file_get(dentry); + r = __debugfs_file_get(dentry, DBGFS_GET_REGULAR); if (r) return r == -EIO ? -ENOENT : r; - real_fops = debugfs_real_fops(filp); - real_fops = fops_get(real_fops); - if (!real_fops) { + r = debugfs_locked_down(inode, filp, real_fops); + if (r) + goto out; + + if (!fops_get(real_fops)) { +#ifdef CONFIG_MODULES + if (real_fops->owner && + real_fops->owner->state == MODULE_STATE_GOING) { + r = -ENXIO; + goto out; + } +#endif + /* Huh? Module did not clean up after itself at exit? */ WARN(1, "debugfs file owner did not clean up at exit: %pd", dentry); @@ -172,61 +328,93 @@ const struct file_operations debugfs_open_proxy_file_operations = { #define PROTO(args...) args #define ARGS(args...) args -#define FULL_PROXY_FUNC(name, ret_type, filp, proto, args) \ +#define FULL_PROXY_FUNC(name, ret_type, filp, proto, args, bit, ret) \ static ret_type full_proxy_ ## name(proto) \ { \ - struct dentry *dentry = F_DENTRY(filp); \ - const struct file_operations *real_fops; \ + struct dentry *dentry = F_DENTRY(filp); \ + struct debugfs_fsdata *fsd = dentry->d_fsdata; \ ret_type r; \ \ + if (!(fsd->methods & bit)) \ + return ret; \ r = debugfs_file_get(dentry); \ if (unlikely(r)) \ return r; \ - real_fops = debugfs_real_fops(filp); \ - r = real_fops->name(args); \ + r = fsd->real_fops->name(args); \ debugfs_file_put(dentry); \ return r; \ } +#define SHORT_PROXY_FUNC(name, ret_type, filp, proto, args, bit, ret) \ +static ret_type short_proxy_ ## name(proto) \ +{ \ + struct dentry *dentry = F_DENTRY(filp); \ + struct debugfs_fsdata *fsd = dentry->d_fsdata; \ + ret_type r; \ + \ + if (!(fsd->methods & bit)) \ + return ret; \ + r = debugfs_file_get(dentry); \ + if (unlikely(r)) \ + return r; \ + r = fsd->short_fops->name(args); \ + debugfs_file_put(dentry); \ + return r; \ +} + +SHORT_PROXY_FUNC(llseek, loff_t, filp, + PROTO(struct file *filp, loff_t offset, int whence), + ARGS(filp, offset, whence), HAS_LSEEK, -ESPIPE); + FULL_PROXY_FUNC(llseek, loff_t, filp, PROTO(struct file *filp, loff_t offset, int whence), - ARGS(filp, offset, whence)); + ARGS(filp, offset, whence), HAS_LSEEK, -ESPIPE); + +SHORT_PROXY_FUNC(read, ssize_t, filp, + PROTO(struct file *filp, char __user *buf, size_t size, + loff_t *ppos), + ARGS(filp, buf, size, ppos), HAS_READ, -EINVAL); FULL_PROXY_FUNC(read, ssize_t, filp, PROTO(struct file *filp, char __user *buf, size_t size, loff_t *ppos), - ARGS(filp, buf, size, ppos)); + ARGS(filp, buf, size, ppos), HAS_READ, -EINVAL); + +SHORT_PROXY_FUNC(write, ssize_t, filp, + PROTO(struct file *filp, const char __user *buf, + size_t size, loff_t *ppos), + ARGS(filp, buf, size, ppos), HAS_WRITE, -EINVAL); FULL_PROXY_FUNC(write, ssize_t, filp, - PROTO(struct file *filp, const char __user *buf, size_t size, - loff_t *ppos), - ARGS(filp, buf, size, ppos)); + PROTO(struct file *filp, const char __user *buf, + size_t size, loff_t *ppos), + ARGS(filp, buf, size, ppos), HAS_WRITE, -EINVAL); FULL_PROXY_FUNC(unlocked_ioctl, long, filp, PROTO(struct file *filp, unsigned int cmd, unsigned long arg), - ARGS(filp, cmd, arg)); + ARGS(filp, cmd, arg), HAS_IOCTL, -ENOTTY); static __poll_t full_proxy_poll(struct file *filp, struct poll_table_struct *wait) { struct dentry *dentry = F_DENTRY(filp); + struct debugfs_fsdata *fsd = dentry->d_fsdata; __poll_t r = 0; - const struct file_operations *real_fops; + if (!(fsd->methods & HAS_POLL)) + return DEFAULT_POLLMASK; if (debugfs_file_get(dentry)) return EPOLLHUP; - real_fops = debugfs_real_fops(filp); - r = real_fops->poll(filp, wait); + r = fsd->real_fops->poll(filp, wait); debugfs_file_put(dentry); return r; } -static int full_proxy_release(struct inode *inode, struct file *filp) +static int full_proxy_release(struct inode *inode, struct file *file) { - const struct dentry *dentry = F_DENTRY(filp); - const struct file_operations *real_fops = debugfs_real_fops(filp); - const struct file_operations *proxy_fops = filp->f_op; + struct debugfs_fsdata *fsd = F_DENTRY(file)->d_fsdata; + const struct file_operations *real_fops = fsd->real_fops; int r = 0; /* @@ -236,44 +424,38 @@ static int full_proxy_release(struct inode *inode, struct file *filp) * ->i_private is still being meaningful here. */ if (real_fops->release) - r = real_fops->release(inode, filp); + r = real_fops->release(inode, file); - replace_fops(filp, d_inode(dentry)->i_fop); - kfree((void *)proxy_fops); fops_put(real_fops); return r; } -static void __full_proxy_fops_init(struct file_operations *proxy_fops, - const struct file_operations *real_fops) -{ - proxy_fops->release = full_proxy_release; - if (real_fops->llseek) - proxy_fops->llseek = full_proxy_llseek; - if (real_fops->read) - proxy_fops->read = full_proxy_read; - if (real_fops->write) - proxy_fops->write = full_proxy_write; - if (real_fops->poll) - proxy_fops->poll = full_proxy_poll; - if (real_fops->unlocked_ioctl) - proxy_fops->unlocked_ioctl = full_proxy_unlocked_ioctl; -} - -static int full_proxy_open(struct inode *inode, struct file *filp) +static int full_proxy_open_regular(struct inode *inode, struct file *filp) { struct dentry *dentry = F_DENTRY(filp); - const struct file_operations *real_fops = NULL; - struct file_operations *proxy_fops = NULL; + const struct file_operations *real_fops; + struct debugfs_fsdata *fsd; int r; - r = debugfs_file_get(dentry); + r = __debugfs_file_get(dentry, DBGFS_GET_REGULAR); if (r) return r == -EIO ? -ENOENT : r; - real_fops = debugfs_real_fops(filp); - real_fops = fops_get(real_fops); - if (!real_fops) { + fsd = dentry->d_fsdata; + real_fops = fsd->real_fops; + r = debugfs_locked_down(inode, filp, real_fops); + if (r) + goto out; + + if (!fops_get(real_fops)) { +#ifdef CONFIG_MODULES + if (real_fops->owner && + real_fops->owner->state == MODULE_STATE_GOING) { + r = -ENXIO; + goto out; + } +#endif + /* Huh? Module did not cleanup after itself at exit? */ WARN(1, "debugfs file owner did not clean up at exit: %pd", dentry); @@ -281,38 +463,52 @@ static int full_proxy_open(struct inode *inode, struct file *filp) goto out; } - proxy_fops = kzalloc(sizeof(*proxy_fops), GFP_KERNEL); - if (!proxy_fops) { - r = -ENOMEM; - goto free_proxy; - } - __full_proxy_fops_init(proxy_fops, real_fops); - replace_fops(filp, proxy_fops); - if (real_fops->open) { r = real_fops->open(inode, filp); if (r) { - replace_fops(filp, d_inode(dentry)->i_fop); - goto free_proxy; - } else if (filp->f_op != proxy_fops) { + fops_put(real_fops); + } else if (filp->f_op != &debugfs_full_proxy_file_operations) { /* No protection against file removal anymore. */ WARN(1, "debugfs file owner replaced proxy fops: %pd", dentry); - goto free_proxy; + fops_put(real_fops); } } - - goto out; -free_proxy: - kfree(proxy_fops); - fops_put(real_fops); out: debugfs_file_put(dentry); return r; } const struct file_operations debugfs_full_proxy_file_operations = { - .open = full_proxy_open, + .open = full_proxy_open_regular, + .release = full_proxy_release, + .llseek = full_proxy_llseek, + .read = full_proxy_read, + .write = full_proxy_write, + .poll = full_proxy_poll, + .unlocked_ioctl = full_proxy_unlocked_ioctl +}; + +static int full_proxy_open_short(struct inode *inode, struct file *filp) +{ + struct dentry *dentry = F_DENTRY(filp); + int r; + + r = __debugfs_file_get(dentry, DBGFS_GET_SHORT); + if (r) + return r == -EIO ? -ENOENT : r; + r = debugfs_locked_down(inode, filp, NULL); + if (!r) + r = simple_open(inode, filp); + debugfs_file_put(dentry); + return r; +} + +const struct file_operations debugfs_full_short_proxy_file_operations = { + .open = full_proxy_open_short, + .llseek = short_proxy_llseek, + .read = short_proxy_read, + .write = short_proxy_write, }; ssize_t debugfs_attr_read(struct file *file, char __user *buf, @@ -330,8 +526,8 @@ ssize_t debugfs_attr_read(struct file *file, char __user *buf, } EXPORT_SYMBOL_GPL(debugfs_attr_read); -ssize_t debugfs_attr_write(struct file *file, const char __user *buf, - size_t len, loff_t *ppos) +static ssize_t debugfs_attr_write_xsigned(struct file *file, const char __user *buf, + size_t len, loff_t *ppos, bool is_signed) { struct dentry *dentry = F_DENTRY(file); ssize_t ret; @@ -339,12 +535,28 @@ ssize_t debugfs_attr_write(struct file *file, const char __user *buf, ret = debugfs_file_get(dentry); if (unlikely(ret)) return ret; - ret = simple_attr_write(file, buf, len, ppos); + if (is_signed) + ret = simple_attr_write_signed(file, buf, len, ppos); + else + ret = simple_attr_write(file, buf, len, ppos); debugfs_file_put(dentry); return ret; } + +ssize_t debugfs_attr_write(struct file *file, const char __user *buf, + size_t len, loff_t *ppos) +{ + return debugfs_attr_write_xsigned(file, buf, len, ppos, false); +} EXPORT_SYMBOL_GPL(debugfs_attr_write); +ssize_t debugfs_attr_write_signed(struct file *file, const char __user *buf, + size_t len, loff_t *ppos) +{ + return debugfs_attr_write_xsigned(file, buf, len, ppos, true); +} +EXPORT_SYMBOL_GPL(debugfs_attr_write_signed); + static struct dentry *debugfs_create_mode_unsafe(const char *name, umode_t mode, struct dentry *parent, void *value, const struct file_operations *fops, @@ -390,21 +602,11 @@ DEFINE_DEBUGFS_ATTRIBUTE(fops_u8_wo, NULL, debugfs_u8_set, "%llu\n"); * This function creates a file in debugfs with the given name that * contains the value of the variable @value. If the @mode variable is so * set, it can be read from, and written to. - * - * This function will return a pointer to a dentry if it succeeds. This - * pointer must be passed to the debugfs_remove() function when the file is - * to be removed (no automatic cleanup happens if your module is unloaded, - * you are responsible here.) If an error occurs, %NULL will be returned. - * - * If debugfs is not enabled in the kernel, the value -%ENODEV will be - * returned. It is not wise to check for this value, but rather, check for - * %NULL or !%NULL instead as to eliminate the need for #ifdef in the calling - * code. */ -struct dentry *debugfs_create_u8(const char *name, umode_t mode, - struct dentry *parent, u8 *value) +void debugfs_create_u8(const char *name, umode_t mode, struct dentry *parent, + u8 *value) { - return debugfs_create_mode_unsafe(name, mode, parent, value, &fops_u8, + debugfs_create_mode_unsafe(name, mode, parent, value, &fops_u8, &fops_u8_ro, &fops_u8_wo); } EXPORT_SYMBOL_GPL(debugfs_create_u8); @@ -436,21 +638,11 @@ DEFINE_DEBUGFS_ATTRIBUTE(fops_u16_wo, NULL, debugfs_u16_set, "%llu\n"); * This function creates a file in debugfs with the given name that * contains the value of the variable @value. If the @mode variable is so * set, it can be read from, and written to. - * - * This function will return a pointer to a dentry if it succeeds. This - * pointer must be passed to the debugfs_remove() function when the file is - * to be removed (no automatic cleanup happens if your module is unloaded, - * you are responsible here.) If an error occurs, %NULL will be returned. - * - * If debugfs is not enabled in the kernel, the value -%ENODEV will be - * returned. It is not wise to check for this value, but rather, check for - * %NULL or !%NULL instead as to eliminate the need for #ifdef in the calling - * code. */ -struct dentry *debugfs_create_u16(const char *name, umode_t mode, - struct dentry *parent, u16 *value) +void debugfs_create_u16(const char *name, umode_t mode, struct dentry *parent, + u16 *value) { - return debugfs_create_mode_unsafe(name, mode, parent, value, &fops_u16, + debugfs_create_mode_unsafe(name, mode, parent, value, &fops_u16, &fops_u16_ro, &fops_u16_wo); } EXPORT_SYMBOL_GPL(debugfs_create_u16); @@ -482,21 +674,11 @@ DEFINE_DEBUGFS_ATTRIBUTE(fops_u32_wo, NULL, debugfs_u32_set, "%llu\n"); * This function creates a file in debugfs with the given name that * contains the value of the variable @value. If the @mode variable is so * set, it can be read from, and written to. - * - * This function will return a pointer to a dentry if it succeeds. This - * pointer must be passed to the debugfs_remove() function when the file is - * to be removed (no automatic cleanup happens if your module is unloaded, - * you are responsible here.) If an error occurs, %NULL will be returned. - * - * If debugfs is not enabled in the kernel, the value -%ENODEV will be - * returned. It is not wise to check for this value, but rather, check for - * %NULL or !%NULL instead as to eliminate the need for #ifdef in the calling - * code. */ -struct dentry *debugfs_create_u32(const char *name, umode_t mode, - struct dentry *parent, u32 *value) +void debugfs_create_u32(const char *name, umode_t mode, struct dentry *parent, + u32 *value) { - return debugfs_create_mode_unsafe(name, mode, parent, value, &fops_u32, + debugfs_create_mode_unsafe(name, mode, parent, value, &fops_u32, &fops_u32_ro, &fops_u32_wo); } EXPORT_SYMBOL_GPL(debugfs_create_u32); @@ -529,21 +711,11 @@ DEFINE_DEBUGFS_ATTRIBUTE(fops_u64_wo, NULL, debugfs_u64_set, "%llu\n"); * This function creates a file in debugfs with the given name that * contains the value of the variable @value. If the @mode variable is so * set, it can be read from, and written to. - * - * This function will return a pointer to a dentry if it succeeds. This - * pointer must be passed to the debugfs_remove() function when the file is - * to be removed (no automatic cleanup happens if your module is unloaded, - * you are responsible here.) If an error occurs, %NULL will be returned. - * - * If debugfs is not enabled in the kernel, the value -%ENODEV will be - * returned. It is not wise to check for this value, but rather, check for - * %NULL or !%NULL instead as to eliminate the need for #ifdef in the calling - * code. */ -struct dentry *debugfs_create_u64(const char *name, umode_t mode, - struct dentry *parent, u64 *value) +void debugfs_create_u64(const char *name, umode_t mode, struct dentry *parent, + u64 *value) { - return debugfs_create_mode_unsafe(name, mode, parent, value, &fops_u64, + debugfs_create_mode_unsafe(name, mode, parent, value, &fops_u64, &fops_u64_ro, &fops_u64_wo); } EXPORT_SYMBOL_GPL(debugfs_create_u64); @@ -578,23 +750,12 @@ DEFINE_DEBUGFS_ATTRIBUTE(fops_ulong_wo, NULL, debugfs_ulong_set, "%llu\n"); * This function creates a file in debugfs with the given name that * contains the value of the variable @value. If the @mode variable is so * set, it can be read from, and written to. - * - * This function will return a pointer to a dentry if it succeeds. This - * pointer must be passed to the debugfs_remove() function when the file is - * to be removed (no automatic cleanup happens if your module is unloaded, - * you are responsible here.) If an error occurs, %NULL will be returned. - * - * If debugfs is not enabled in the kernel, the value -%ENODEV will be - * returned. It is not wise to check for this value, but rather, check for - * %NULL or !%NULL instead as to eliminate the need for #ifdef in the calling - * code. */ -struct dentry *debugfs_create_ulong(const char *name, umode_t mode, - struct dentry *parent, unsigned long *value) +void debugfs_create_ulong(const char *name, umode_t mode, struct dentry *parent, + unsigned long *value) { - return debugfs_create_mode_unsafe(name, mode, parent, value, - &fops_ulong, &fops_ulong_ro, - &fops_ulong_wo); + debugfs_create_mode_unsafe(name, mode, parent, value, &fops_ulong, + &fops_ulong_ro, &fops_ulong_wo); } EXPORT_SYMBOL_GPL(debugfs_create_ulong); @@ -635,10 +796,10 @@ DEFINE_DEBUGFS_ATTRIBUTE(fops_x64_wo, NULL, debugfs_u64_set, "0x%016llx\n"); * @value: a pointer to the variable that the file should read to and write * from. */ -struct dentry *debugfs_create_x8(const char *name, umode_t mode, - struct dentry *parent, u8 *value) +void debugfs_create_x8(const char *name, umode_t mode, struct dentry *parent, + u8 *value) { - return debugfs_create_mode_unsafe(name, mode, parent, value, &fops_x8, + debugfs_create_mode_unsafe(name, mode, parent, value, &fops_x8, &fops_x8_ro, &fops_x8_wo); } EXPORT_SYMBOL_GPL(debugfs_create_x8); @@ -653,10 +814,10 @@ EXPORT_SYMBOL_GPL(debugfs_create_x8); * @value: a pointer to the variable that the file should read to and write * from. */ -struct dentry *debugfs_create_x16(const char *name, umode_t mode, - struct dentry *parent, u16 *value) +void debugfs_create_x16(const char *name, umode_t mode, struct dentry *parent, + u16 *value) { - return debugfs_create_mode_unsafe(name, mode, parent, value, &fops_x16, + debugfs_create_mode_unsafe(name, mode, parent, value, &fops_x16, &fops_x16_ro, &fops_x16_wo); } EXPORT_SYMBOL_GPL(debugfs_create_x16); @@ -671,10 +832,10 @@ EXPORT_SYMBOL_GPL(debugfs_create_x16); * @value: a pointer to the variable that the file should read to and write * from. */ -struct dentry *debugfs_create_x32(const char *name, umode_t mode, - struct dentry *parent, u32 *value) +void debugfs_create_x32(const char *name, umode_t mode, struct dentry *parent, + u32 *value) { - return debugfs_create_mode_unsafe(name, mode, parent, value, &fops_x32, + debugfs_create_mode_unsafe(name, mode, parent, value, &fops_x32, &fops_x32_ro, &fops_x32_wo); } EXPORT_SYMBOL_GPL(debugfs_create_x32); @@ -689,10 +850,10 @@ EXPORT_SYMBOL_GPL(debugfs_create_x32); * @value: a pointer to the variable that the file should read to and write * from. */ -struct dentry *debugfs_create_x64(const char *name, umode_t mode, - struct dentry *parent, u64 *value) +void debugfs_create_x64(const char *name, umode_t mode, struct dentry *parent, + u64 *value) { - return debugfs_create_mode_unsafe(name, mode, parent, value, &fops_x64, + debugfs_create_mode_unsafe(name, mode, parent, value, &fops_x64, &fops_x64_ro, &fops_x64_wo); } EXPORT_SYMBOL_GPL(debugfs_create_x64); @@ -723,12 +884,11 @@ DEFINE_DEBUGFS_ATTRIBUTE(fops_size_t_wo, NULL, debugfs_size_t_set, "%llu\n"); * @value: a pointer to the variable that the file should read to and write * from. */ -struct dentry *debugfs_create_size_t(const char *name, umode_t mode, - struct dentry *parent, size_t *value) +void debugfs_create_size_t(const char *name, umode_t mode, + struct dentry *parent, size_t *value) { - return debugfs_create_mode_unsafe(name, mode, parent, value, - &fops_size_t, &fops_size_t_ro, - &fops_size_t_wo); + debugfs_create_mode_unsafe(name, mode, parent, value, &fops_size_t, + &fops_size_t_ro, &fops_size_t_wo); } EXPORT_SYMBOL_GPL(debugfs_create_size_t); @@ -742,11 +902,11 @@ static int debugfs_atomic_t_get(void *data, u64 *val) *val = atomic_read((atomic_t *)data); return 0; } -DEFINE_DEBUGFS_ATTRIBUTE(fops_atomic_t, debugfs_atomic_t_get, +DEFINE_DEBUGFS_ATTRIBUTE_SIGNED(fops_atomic_t, debugfs_atomic_t_get, debugfs_atomic_t_set, "%lld\n"); -DEFINE_DEBUGFS_ATTRIBUTE(fops_atomic_t_ro, debugfs_atomic_t_get, NULL, +DEFINE_DEBUGFS_ATTRIBUTE_SIGNED(fops_atomic_t_ro, debugfs_atomic_t_get, NULL, "%lld\n"); -DEFINE_DEBUGFS_ATTRIBUTE(fops_atomic_t_wo, NULL, debugfs_atomic_t_set, +DEFINE_DEBUGFS_ATTRIBUTE_SIGNED(fops_atomic_t_wo, NULL, debugfs_atomic_t_set, "%lld\n"); /** @@ -760,19 +920,18 @@ DEFINE_DEBUGFS_ATTRIBUTE(fops_atomic_t_wo, NULL, debugfs_atomic_t_set, * @value: a pointer to the variable that the file should read to and write * from. */ -struct dentry *debugfs_create_atomic_t(const char *name, umode_t mode, - struct dentry *parent, atomic_t *value) +void debugfs_create_atomic_t(const char *name, umode_t mode, + struct dentry *parent, atomic_t *value) { - return debugfs_create_mode_unsafe(name, mode, parent, value, - &fops_atomic_t, &fops_atomic_t_ro, - &fops_atomic_t_wo); + debugfs_create_mode_unsafe(name, mode, parent, value, &fops_atomic_t, + &fops_atomic_t_ro, &fops_atomic_t_wo); } EXPORT_SYMBOL_GPL(debugfs_create_atomic_t); ssize_t debugfs_read_file_bool(struct file *file, char __user *user_buf, size_t count, loff_t *ppos) { - char buf[3]; + char buf[2]; bool val; int r; struct dentry *dentry = F_DENTRY(file); @@ -788,7 +947,6 @@ ssize_t debugfs_read_file_bool(struct file *file, char __user *user_buf, else buf[0] = 'N'; buf[1] = '\n'; - buf[2] = 0x00; return simple_read_from_buffer(user_buf, count, ppos, buf, 2); } EXPORT_SYMBOL_GPL(debugfs_read_file_bool); @@ -846,25 +1004,142 @@ static const struct file_operations fops_bool_wo = { * This function creates a file in debugfs with the given name that * contains the value of the variable @value. If the @mode variable is so * set, it can be read from, and written to. - * - * This function will return a pointer to a dentry if it succeeds. This - * pointer must be passed to the debugfs_remove() function when the file is - * to be removed (no automatic cleanup happens if your module is unloaded, - * you are responsible here.) If an error occurs, %NULL will be returned. - * - * If debugfs is not enabled in the kernel, the value -%ENODEV will be - * returned. It is not wise to check for this value, but rather, check for - * %NULL or !%NULL instead as to eliminate the need for #ifdef in the calling - * code. */ -struct dentry *debugfs_create_bool(const char *name, umode_t mode, - struct dentry *parent, bool *value) +void debugfs_create_bool(const char *name, umode_t mode, struct dentry *parent, + bool *value) { - return debugfs_create_mode_unsafe(name, mode, parent, value, &fops_bool, + debugfs_create_mode_unsafe(name, mode, parent, value, &fops_bool, &fops_bool_ro, &fops_bool_wo); } EXPORT_SYMBOL_GPL(debugfs_create_bool); +ssize_t debugfs_read_file_str(struct file *file, char __user *user_buf, + size_t count, loff_t *ppos) +{ + struct dentry *dentry = F_DENTRY(file); + char *str, *copy = NULL; + int copy_len, len; + ssize_t ret; + + ret = debugfs_file_get(dentry); + if (unlikely(ret)) + return ret; + + str = *(char **)file->private_data; + len = strlen(str) + 1; + copy = kmalloc(len, GFP_KERNEL); + if (!copy) { + debugfs_file_put(dentry); + return -ENOMEM; + } + + copy_len = strscpy(copy, str, len); + debugfs_file_put(dentry); + if (copy_len < 0) { + kfree(copy); + return copy_len; + } + + copy[copy_len] = '\n'; + + ret = simple_read_from_buffer(user_buf, count, ppos, copy, len); + kfree(copy); + + return ret; +} +EXPORT_SYMBOL_GPL(debugfs_create_str); + +static ssize_t debugfs_write_file_str(struct file *file, const char __user *user_buf, + size_t count, loff_t *ppos) +{ + struct dentry *dentry = F_DENTRY(file); + char *old, *new = NULL; + int pos = *ppos; + int r; + + r = debugfs_file_get(dentry); + if (unlikely(r)) + return r; + + old = *(char **)file->private_data; + + /* only allow strict concatenation */ + r = -EINVAL; + if (pos && pos != strlen(old)) + goto error; + + r = -E2BIG; + if (pos + count + 1 > PAGE_SIZE) + goto error; + + r = -ENOMEM; + new = kmalloc(pos + count + 1, GFP_KERNEL); + if (!new) + goto error; + + if (pos) + memcpy(new, old, pos); + + r = -EFAULT; + if (copy_from_user(new + pos, user_buf, count)) + goto error; + + new[pos + count] = '\0'; + strim(new); + + rcu_assign_pointer(*(char __rcu **)file->private_data, new); + synchronize_rcu(); + kfree(old); + + debugfs_file_put(dentry); + return count; + +error: + kfree(new); + debugfs_file_put(dentry); + return r; +} + +static const struct file_operations fops_str = { + .read = debugfs_read_file_str, + .write = debugfs_write_file_str, + .open = simple_open, + .llseek = default_llseek, +}; + +static const struct file_operations fops_str_ro = { + .read = debugfs_read_file_str, + .open = simple_open, + .llseek = default_llseek, +}; + +static const struct file_operations fops_str_wo = { + .write = debugfs_write_file_str, + .open = simple_open, + .llseek = default_llseek, +}; + +/** + * debugfs_create_str - create a debugfs file that is used to read and write a string value + * @name: a pointer to a string containing the name of the file to create. + * @mode: the permission that the file should have + * @parent: a pointer to the parent dentry for this file. This should be a + * directory dentry if set. If this parameter is %NULL, then the + * file will be created in the root of the debugfs filesystem. + * @value: a pointer to the variable that the file should read to and write + * from. + * + * This function creates a file in debugfs with the given name that + * contains the value of the variable @value. If the @mode variable is so + * set, it can be read from, and written to. + */ +void debugfs_create_str(const char *name, umode_t mode, + struct dentry *parent, char **value) +{ + debugfs_create_mode_unsafe(name, mode, parent, value, &fops_str, + &fops_str_ro, &fops_str_wo); +} + static ssize_t read_file_blob(struct file *file, char __user *user_buf, size_t count, loff_t *ppos) { @@ -881,14 +1156,33 @@ static ssize_t read_file_blob(struct file *file, char __user *user_buf, return r; } +static ssize_t write_file_blob(struct file *file, const char __user *user_buf, + size_t count, loff_t *ppos) +{ + struct debugfs_blob_wrapper *blob = file->private_data; + struct dentry *dentry = F_DENTRY(file); + ssize_t r; + + r = debugfs_file_get(dentry); + if (unlikely(r)) + return r; + r = simple_write_to_buffer(blob->data, blob->size, ppos, user_buf, + count); + + debugfs_file_put(dentry); + return r; +} + static const struct file_operations fops_blob = { .read = read_file_blob, + .write = write_file_blob, .open = simple_open, .llseek = default_llseek, }; /** - * debugfs_create_blob - create a debugfs file that is used to read a binary blob + * debugfs_create_blob - create a debugfs file that is used to read and write + * a binary blob * @name: a pointer to a string containing the name of the file to create. * @mode: the permission that the file should have * @parent: a pointer to the parent dentry for this file. This should be a @@ -899,31 +1193,25 @@ static const struct file_operations fops_blob = { * * This function creates a file in debugfs with the given name that exports * @blob->data as a binary blob. If the @mode variable is so set it can be - * read from. Writing is not supported. + * read from and written to. * * This function will return a pointer to a dentry if it succeeds. This * pointer must be passed to the debugfs_remove() function when the file is * to be removed (no automatic cleanup happens if your module is unloaded, - * you are responsible here.) If an error occurs, %NULL will be returned. + * you are responsible here.) If an error occurs, ERR_PTR(-ERROR) will be + * returned. * - * If debugfs is not enabled in the kernel, the value -%ENODEV will be - * returned. It is not wise to check for this value, but rather, check for - * %NULL or !%NULL instead as to eliminate the need for #ifdef in the calling - * code. + * If debugfs is not enabled in the kernel, the value ERR_PTR(-ENODEV) will + * be returned. */ struct dentry *debugfs_create_blob(const char *name, umode_t mode, struct dentry *parent, struct debugfs_blob_wrapper *blob) { - return debugfs_create_file_unsafe(name, mode, parent, blob, &fops_blob); + return debugfs_create_file_unsafe(name, mode & 0644, parent, blob, &fops_blob); } EXPORT_SYMBOL_GPL(debugfs_create_blob); -struct array_data { - void *array; - u32 elements; -}; - static size_t u32_format_array(char *buf, size_t bufsize, u32 *array, int array_size) { @@ -944,8 +1232,8 @@ static size_t u32_format_array(char *buf, size_t bufsize, static int u32_array_open(struct inode *inode, struct file *file) { - struct array_data *data = inode->i_private; - int size, elements = data->elements; + struct debugfs_u32_array *data = inode->i_private; + int size, elements = data->n_elements; char *buf; /* @@ -960,7 +1248,7 @@ static int u32_array_open(struct inode *inode, struct file *file) buf[size] = 0; file->private_data = buf; - u32_format_array(buf, size, data->array, data->elements); + u32_format_array(buf, size, data->array, data->n_elements); return nonseekable_open(inode, file); } @@ -986,7 +1274,6 @@ static const struct file_operations u32_array_fops = { .open = u32_array_open, .release = u32_array_release, .read = u32_array_read, - .llseek = no_llseek, }; /** @@ -997,31 +1284,18 @@ static const struct file_operations u32_array_fops = { * @parent: a pointer to the parent dentry for this file. This should be a * directory dentry if set. If this parameter is %NULL, then the * file will be created in the root of the debugfs filesystem. - * @array: u32 array that provides data. - * @elements: total number of elements in the array. + * @array: wrapper struct containing data pointer and size of the array. * * This function creates a file in debugfs with the given name that exports * @array as data. If the @mode variable is so set it can be read from. * Writing is not supported. Seek within the file is also not supported. * Once array is created its size can not be changed. - * - * The function returns a pointer to dentry on success. If debugfs is not - * enabled in the kernel, the value -%ENODEV will be returned. */ -struct dentry *debugfs_create_u32_array(const char *name, umode_t mode, - struct dentry *parent, - u32 *array, u32 elements) +void debugfs_create_u32_array(const char *name, umode_t mode, + struct dentry *parent, + struct debugfs_u32_array *array) { - struct array_data *data = kmalloc(sizeof(*data), GFP_KERNEL); - - if (data == NULL) - return NULL; - - data->array = array; - data->elements = elements; - - return debugfs_create_file_unsafe(name, mode, parent, data, - &u32_array_fops); + debugfs_create_file_unsafe(name, mode, parent, array, &u32_array_fops); } EXPORT_SYMBOL_GPL(debugfs_create_u32_array); @@ -1064,25 +1338,22 @@ void debugfs_print_regs32(struct seq_file *s, const struct debugfs_reg32 *regs, } EXPORT_SYMBOL_GPL(debugfs_print_regs32); -static int debugfs_show_regset32(struct seq_file *s, void *data) +static int debugfs_regset32_show(struct seq_file *s, void *data) { struct debugfs_regset32 *regset = s->private; + if (regset->dev) + pm_runtime_get_sync(regset->dev); + debugfs_print_regs32(s, regset->regs, regset->nregs, regset->base, ""); - return 0; -} -static int debugfs_open_regset32(struct inode *inode, struct file *file) -{ - return single_open(file, debugfs_show_regset32, inode->i_private); + if (regset->dev) + pm_runtime_put(regset->dev); + + return 0; } -static const struct file_operations fops_regset32 = { - .open = debugfs_open_regset32, - .read = seq_read, - .llseek = seq_lseek, - .release = single_release, -}; +DEFINE_SHOW_ATTRIBUTE(debugfs_regset32); /** * debugfs_create_regset32 - create a debugfs file that returns register values @@ -1098,22 +1369,12 @@ static const struct file_operations fops_regset32 = { * This function creates a file in debugfs with the given name that reports * the names and values of a set of 32-bit registers. If the @mode variable * is so set it can be read from. Writing is not supported. - * - * This function will return a pointer to a dentry if it succeeds. This - * pointer must be passed to the debugfs_remove() function when the file is - * to be removed (no automatic cleanup happens if your module is unloaded, - * you are responsible here.) If an error occurs, %NULL will be returned. - * - * If debugfs is not enabled in the kernel, the value -%ENODEV will be - * returned. It is not wise to check for this value, but rather, check for - * %NULL or !%NULL instead as to eliminate the need for #ifdef in the calling - * code. */ -struct dentry *debugfs_create_regset32(const char *name, umode_t mode, - struct dentry *parent, - struct debugfs_regset32 *regset) +void debugfs_create_regset32(const char *name, umode_t mode, + struct dentry *parent, + struct debugfs_regset32 *regset) { - return debugfs_create_file(name, mode, parent, regset, &fops_regset32); + debugfs_create_file(name, mode, parent, regset, &debugfs_regset32_fops); } EXPORT_SYMBOL_GPL(debugfs_create_regset32); @@ -1149,25 +1410,23 @@ static const struct file_operations debugfs_devm_entry_ops = { * file will be created in the root of the debugfs filesystem. * @read_fn: function pointer called to print the seq_file content. */ -struct dentry *debugfs_create_devm_seqfile(struct device *dev, const char *name, - struct dentry *parent, - int (*read_fn)(struct seq_file *s, - void *data)) +void debugfs_create_devm_seqfile(struct device *dev, const char *name, + struct dentry *parent, + int (*read_fn)(struct seq_file *s, void *data)) { struct debugfs_devm_entry *entry; if (IS_ERR(parent)) - return ERR_PTR(-ENOENT); + return; entry = devm_kzalloc(dev, sizeof(*entry), GFP_KERNEL); if (!entry) - return ERR_PTR(-ENOMEM); + return; entry->read = read_fn; entry->dev = dev; - return debugfs_create_file(name, S_IRUGO, parent, entry, - &debugfs_devm_entry_ops); + debugfs_create_file(name, S_IRUGO, parent, entry, + &debugfs_devm_entry_ops); } EXPORT_SYMBOL_GPL(debugfs_create_devm_seqfile); - diff --git a/fs/debugfs/inode.c b/fs/debugfs/inode.c index 13b01351dd1c..4b263c328ed2 100644 --- a/fs/debugfs/inode.c +++ b/fs/debugfs/inode.c @@ -2,16 +2,20 @@ /* * inode.c - part of debugfs, a tiny little debug file system * - * Copyright (C) 2004 Greg Kroah-Hartman <greg@kroah.com> + * Copyright (C) 2004,2019 Greg Kroah-Hartman <greg@kroah.com> * Copyright (C) 2004 IBM Inc. + * Copyright (C) 2019 Linux Foundation <gregkh@linuxfoundation.org> * * debugfs is for people to use instead of /proc or /sys. * See ./Documentation/core-api/kernel-api.rst for more details. */ +#define pr_fmt(fmt) "debugfs: " fmt + #include <linux/module.h> #include <linux/fs.h> -#include <linux/mount.h> +#include <linux/fs_context.h> +#include <linux/fs_parser.h> #include <linux/pagemap.h> #include <linux/init.h> #include <linux/kobject.h> @@ -20,9 +24,9 @@ #include <linux/fsnotify.h> #include <linux/string.h> #include <linux/seq_file.h> -#include <linux/parser.h> #include <linux/magic.h> #include <linux/slab.h> +#include <linux/security.h> #include "internal.h" @@ -31,220 +35,298 @@ static struct vfsmount *debugfs_mount; static int debugfs_mount_count; static bool debugfs_registered; +static bool debugfs_enabled __ro_after_init = IS_ENABLED(CONFIG_DEBUG_FS_ALLOW_ALL); + +/* + * Don't allow access attributes to be changed whilst the kernel is locked down + * so that we can use the file mode as part of a heuristic to determine whether + * to lock down individual files. + */ +static int debugfs_setattr(struct mnt_idmap *idmap, + struct dentry *dentry, struct iattr *ia) +{ + int ret; + + if (ia->ia_valid & (ATTR_MODE | ATTR_UID | ATTR_GID)) { + ret = security_locked_down(LOCKDOWN_DEBUGFS); + if (ret) + return ret; + } + return simple_setattr(&nop_mnt_idmap, dentry, ia); +} + +static const struct inode_operations debugfs_file_inode_operations = { + .setattr = debugfs_setattr, +}; +static const struct inode_operations debugfs_dir_inode_operations = { + .lookup = simple_lookup, + .setattr = debugfs_setattr, +}; +static const struct inode_operations debugfs_symlink_inode_operations = { + .get_link = simple_get_link, + .setattr = debugfs_setattr, +}; static struct inode *debugfs_get_inode(struct super_block *sb) { struct inode *inode = new_inode(sb); if (inode) { inode->i_ino = get_next_ino(); - inode->i_atime = inode->i_mtime = - inode->i_ctime = current_time(inode); + simple_inode_init_ts(inode); } return inode; } -struct debugfs_mount_opts { +struct debugfs_fs_info { kuid_t uid; kgid_t gid; umode_t mode; + /* Opt_* bitfield. */ + unsigned int opts; }; enum { Opt_uid, Opt_gid, Opt_mode, - Opt_err + Opt_source, }; -static const match_table_t tokens = { - {Opt_uid, "uid=%u"}, - {Opt_gid, "gid=%u"}, - {Opt_mode, "mode=%o"}, - {Opt_err, NULL} +static const struct fs_parameter_spec debugfs_param_specs[] = { + fsparam_gid ("gid", Opt_gid), + fsparam_u32oct ("mode", Opt_mode), + fsparam_uid ("uid", Opt_uid), + fsparam_string ("source", Opt_source), + {} }; -struct debugfs_fs_info { - struct debugfs_mount_opts mount_opts; -}; - -static int debugfs_parse_options(char *data, struct debugfs_mount_opts *opts) +static int debugfs_parse_param(struct fs_context *fc, struct fs_parameter *param) { - substring_t args[MAX_OPT_ARGS]; - int option; - int token; - kuid_t uid; - kgid_t gid; - char *p; - - opts->mode = DEBUGFS_DEFAULT_MODE; - - while ((p = strsep(&data, ",")) != NULL) { - if (!*p) - continue; - - token = match_token(p, tokens, args); - switch (token) { - case Opt_uid: - if (match_int(&args[0], &option)) - return -EINVAL; - uid = make_kuid(current_user_ns(), option); - if (!uid_valid(uid)) - return -EINVAL; - opts->uid = uid; - break; - case Opt_gid: - if (match_int(&args[0], &option)) - return -EINVAL; - gid = make_kgid(current_user_ns(), option); - if (!gid_valid(gid)) - return -EINVAL; - opts->gid = gid; - break; - case Opt_mode: - if (match_octal(&args[0], &option)) - return -EINVAL; - opts->mode = option & S_IALLUGO; - break; + struct debugfs_fs_info *opts = fc->s_fs_info; + struct fs_parse_result result; + int opt; + + opt = fs_parse(fc, debugfs_param_specs, param, &result); + if (opt < 0) { /* - * We might like to report bad mount options here; - * but traditionally debugfs has ignored all mount options - */ - } + * We might like to report bad mount options here; but + * traditionally debugfs has ignored all mount options + */ + if (opt == -ENOPARAM) + return 0; + + return opt; + } + + switch (opt) { + case Opt_uid: + opts->uid = result.uid; + break; + case Opt_gid: + opts->gid = result.gid; + break; + case Opt_mode: + opts->mode = result.uint_32 & S_IALLUGO; + break; + case Opt_source: + if (fc->source) + return invalfc(fc, "Multiple sources specified"); + fc->source = param->string; + param->string = NULL; + break; + /* + * We might like to report bad mount options here; + * but traditionally debugfs has ignored all mount options + */ } + opts->opts |= BIT(opt); + return 0; } -static int debugfs_apply_options(struct super_block *sb) +static void _debugfs_apply_options(struct super_block *sb, bool remount) { struct debugfs_fs_info *fsi = sb->s_fs_info; struct inode *inode = d_inode(sb->s_root); - struct debugfs_mount_opts *opts = &fsi->mount_opts; - inode->i_mode &= ~S_IALLUGO; - inode->i_mode |= opts->mode; + /* + * On remount, only reset mode/uid/gid if they were provided as mount + * options. + */ - inode->i_uid = opts->uid; - inode->i_gid = opts->gid; + if (!remount || fsi->opts & BIT(Opt_mode)) { + inode->i_mode &= ~S_IALLUGO; + inode->i_mode |= fsi->mode; + } - return 0; + if (!remount || fsi->opts & BIT(Opt_uid)) + inode->i_uid = fsi->uid; + + if (!remount || fsi->opts & BIT(Opt_gid)) + inode->i_gid = fsi->gid; } -static int debugfs_remount(struct super_block *sb, int *flags, char *data) +static void debugfs_apply_options(struct super_block *sb) { - int err; - struct debugfs_fs_info *fsi = sb->s_fs_info; + _debugfs_apply_options(sb, false); +} + +static void debugfs_apply_options_remount(struct super_block *sb) +{ + _debugfs_apply_options(sb, true); +} + +static int debugfs_reconfigure(struct fs_context *fc) +{ + struct super_block *sb = fc->root->d_sb; + struct debugfs_fs_info *sb_opts = sb->s_fs_info; + struct debugfs_fs_info *new_opts = fc->s_fs_info; + + if (!new_opts) + return 0; sync_filesystem(sb); - err = debugfs_parse_options(data, &fsi->mount_opts); - if (err) - goto fail; - debugfs_apply_options(sb); + /* structure copy of new mount options to sb */ + *sb_opts = *new_opts; + debugfs_apply_options_remount(sb); -fail: - return err; + return 0; } static int debugfs_show_options(struct seq_file *m, struct dentry *root) { struct debugfs_fs_info *fsi = root->d_sb->s_fs_info; - struct debugfs_mount_opts *opts = &fsi->mount_opts; - if (!uid_eq(opts->uid, GLOBAL_ROOT_UID)) + if (!uid_eq(fsi->uid, GLOBAL_ROOT_UID)) seq_printf(m, ",uid=%u", - from_kuid_munged(&init_user_ns, opts->uid)); - if (!gid_eq(opts->gid, GLOBAL_ROOT_GID)) + from_kuid_munged(&init_user_ns, fsi->uid)); + if (!gid_eq(fsi->gid, GLOBAL_ROOT_GID)) seq_printf(m, ",gid=%u", - from_kgid_munged(&init_user_ns, opts->gid)); - if (opts->mode != DEBUGFS_DEFAULT_MODE) - seq_printf(m, ",mode=%o", opts->mode); + from_kgid_munged(&init_user_ns, fsi->gid)); + if (fsi->mode != DEBUGFS_DEFAULT_MODE) + seq_printf(m, ",mode=%o", fsi->mode); return 0; } -static void debugfs_evict_inode(struct inode *inode) +static struct kmem_cache *debugfs_inode_cachep __ro_after_init; + +static void init_once(void *foo) +{ + struct debugfs_inode_info *info = foo; + inode_init_once(&info->vfs_inode); +} + +static struct inode *debugfs_alloc_inode(struct super_block *sb) +{ + struct debugfs_inode_info *info; + info = alloc_inode_sb(sb, debugfs_inode_cachep, GFP_KERNEL); + if (!info) + return NULL; + return &info->vfs_inode; +} + +static void debugfs_free_inode(struct inode *inode) { - truncate_inode_pages_final(&inode->i_data); - clear_inode(inode); if (S_ISLNK(inode->i_mode)) kfree(inode->i_link); + kmem_cache_free(debugfs_inode_cachep, DEBUGFS_I(inode)); } static const struct super_operations debugfs_super_operations = { .statfs = simple_statfs, - .remount_fs = debugfs_remount, .show_options = debugfs_show_options, - .evict_inode = debugfs_evict_inode, + .alloc_inode = debugfs_alloc_inode, + .free_inode = debugfs_free_inode, }; static void debugfs_release_dentry(struct dentry *dentry) { - void *fsd = dentry->d_fsdata; + struct debugfs_fsdata *fsd = dentry->d_fsdata; - if (!((unsigned long)fsd & DEBUGFS_FSDATA_IS_REAL_FOPS_BIT)) - kfree(dentry->d_fsdata); + if (fsd) { + WARN_ON(!list_empty(&fsd->cancellations)); + mutex_destroy(&fsd->cancellations_mtx); + } + kfree(fsd); } static struct vfsmount *debugfs_automount(struct path *path) { - debugfs_automount_t f; - f = (debugfs_automount_t)path->dentry->d_fsdata; - return f(path->dentry, d_inode(path->dentry)->i_private); + struct inode *inode = path->dentry->d_inode; + + return DEBUGFS_I(inode)->automount(path->dentry, inode->i_private); } static const struct dentry_operations debugfs_dops = { - .d_delete = always_delete_dentry, .d_release = debugfs_release_dentry, .d_automount = debugfs_automount, }; -static int debug_fill_super(struct super_block *sb, void *data, int silent) +static int debugfs_fill_super(struct super_block *sb, struct fs_context *fc) { static const struct tree_descr debug_files[] = {{""}}; - struct debugfs_fs_info *fsi; int err; - fsi = kzalloc(sizeof(struct debugfs_fs_info), GFP_KERNEL); - sb->s_fs_info = fsi; - if (!fsi) { - err = -ENOMEM; - goto fail; - } - - err = debugfs_parse_options(data, &fsi->mount_opts); - if (err) - goto fail; - - err = simple_fill_super(sb, DEBUGFS_MAGIC, debug_files); + err = simple_fill_super(sb, DEBUGFS_MAGIC, debug_files); if (err) - goto fail; + return err; sb->s_op = &debugfs_super_operations; - sb->s_d_op = &debugfs_dops; + set_default_d_op(sb, &debugfs_dops); + sb->s_d_flags |= DCACHE_DONTCACHE; debugfs_apply_options(sb); return 0; +} + +static int debugfs_get_tree(struct fs_context *fc) +{ + int err; -fail: - kfree(fsi); - sb->s_fs_info = NULL; - return err; + err = get_tree_single(fc, debugfs_fill_super); + if (err) + return err; + + return debugfs_reconfigure(fc); } -static struct dentry *debug_mount(struct file_system_type *fs_type, - int flags, const char *dev_name, - void *data) +static void debugfs_free_fc(struct fs_context *fc) { - return mount_single(fs_type, flags, data, debug_fill_super); + kfree(fc->s_fs_info); +} + +static const struct fs_context_operations debugfs_context_ops = { + .free = debugfs_free_fc, + .parse_param = debugfs_parse_param, + .get_tree = debugfs_get_tree, + .reconfigure = debugfs_reconfigure, +}; + +static int debugfs_init_fs_context(struct fs_context *fc) +{ + struct debugfs_fs_info *fsi; + + fsi = kzalloc(sizeof(struct debugfs_fs_info), GFP_KERNEL); + if (!fsi) + return -ENOMEM; + + fsi->mode = DEBUGFS_DEFAULT_MODE; + + fc->s_fs_info = fsi; + fc->ops = &debugfs_context_ops; + return 0; } static struct file_system_type debug_fs_type = { .owner = THIS_MODULE, .name = "debugfs", - .mount = debug_mount, - .kill_sb = kill_litter_super, + .init_fs_context = debugfs_init_fs_context, + .parameters = debugfs_param_specs, + .kill_sb = kill_anon_super, }; MODULE_ALIAS_FS("debugfs"); @@ -264,37 +346,42 @@ struct dentry *debugfs_lookup(const char *name, struct dentry *parent) { struct dentry *dentry; - if (IS_ERR(parent)) + if (!debugfs_initialized() || IS_ERR_OR_NULL(name) || IS_ERR(parent)) return NULL; if (!parent) parent = debugfs_mount->mnt_root; - dentry = lookup_one_len_unlocked(name, parent, strlen(name)); + dentry = lookup_noperm_positive_unlocked(&QSTR(name), parent); if (IS_ERR(dentry)) return NULL; - if (!d_really_is_positive(dentry)) { - dput(dentry); - return NULL; - } return dentry; } EXPORT_SYMBOL_GPL(debugfs_lookup); -static struct dentry *start_creating(const char *name, struct dentry *parent) +static struct dentry *debugfs_start_creating(const char *name, + struct dentry *parent) { struct dentry *dentry; int error; - pr_debug("debugfs: creating file '%s'\n",name); + if (!debugfs_enabled) + return ERR_PTR(-EPERM); + + if (!debugfs_initialized()) + return ERR_PTR(-ENOENT); + + pr_debug("creating file '%s'\n", name); if (IS_ERR(parent)) return parent; error = simple_pin_fs(&debug_fs_type, &debugfs_mount, &debugfs_mount_count); - if (error) + if (error) { + pr_err("Unable to pin filesystem for file '%s'\n", name); return ERR_PTR(error); + } /* If the parent is not specified, we create it in the root. * We need the root dentry to do this, which is in the super @@ -304,39 +391,33 @@ static struct dentry *start_creating(const char *name, struct dentry *parent) if (!parent) parent = debugfs_mount->mnt_root; - inode_lock(d_inode(parent)); - dentry = lookup_one_len(name, parent, strlen(name)); - if (!IS_ERR(dentry) && d_really_is_positive(dentry)) { - dput(dentry); - dentry = ERR_PTR(-EEXIST); - } - + dentry = simple_start_creating(parent, name); if (IS_ERR(dentry)) { - inode_unlock(d_inode(parent)); + if (dentry == ERR_PTR(-EEXIST)) + pr_err("'%s' already exists in '%pd'\n", name, parent); simple_release_fs(&debugfs_mount, &debugfs_mount_count); } - return dentry; } -static struct dentry *failed_creating(struct dentry *dentry) +static struct dentry *debugfs_failed_creating(struct dentry *dentry) { - inode_unlock(d_inode(dentry->d_parent)); - dput(dentry); + simple_done_creating(dentry); simple_release_fs(&debugfs_mount, &debugfs_mount_count); - return NULL; + return ERR_PTR(-ENOMEM); } -static struct dentry *end_creating(struct dentry *dentry) +static struct dentry *debugfs_end_creating(struct dentry *dentry) { - inode_unlock(d_inode(dentry->d_parent)); - return dentry; + simple_done_creating(dentry); + return dentry; // borrowed } static struct dentry *__debugfs_create_file(const char *name, umode_t mode, struct dentry *parent, void *data, + const void *aux, const struct file_operations *proxy_fops, - const struct file_operations *real_fops) + const void *real_fops) { struct dentry *dentry; struct inode *inode; @@ -344,64 +425,54 @@ static struct dentry *__debugfs_create_file(const char *name, umode_t mode, if (!(mode & S_IFMT)) mode |= S_IFREG; BUG_ON(!S_ISREG(mode)); - dentry = start_creating(name, parent); + dentry = debugfs_start_creating(name, parent); if (IS_ERR(dentry)) - return NULL; + return dentry; inode = debugfs_get_inode(dentry->d_sb); - if (unlikely(!inode)) - return failed_creating(dentry); + if (unlikely(!inode)) { + pr_err("out of free dentries, can not create file '%s'\n", + name); + return debugfs_failed_creating(dentry); + } inode->i_mode = mode; inode->i_private = data; + inode->i_op = &debugfs_file_inode_operations; + if (!real_fops) + proxy_fops = &debugfs_noop_file_operations; inode->i_fop = proxy_fops; - dentry->d_fsdata = (void *)((unsigned long)real_fops | - DEBUGFS_FSDATA_IS_REAL_FOPS_BIT); + DEBUGFS_I(inode)->raw = real_fops; + DEBUGFS_I(inode)->aux = (void *)aux; - d_instantiate(dentry, inode); + d_make_persistent(dentry, inode); fsnotify_create(d_inode(dentry->d_parent), dentry); - return end_creating(dentry); + return debugfs_end_creating(dentry); } -/** - * debugfs_create_file - create a file in the debugfs filesystem - * @name: a pointer to a string containing the name of the file to create. - * @mode: the permission that the file should have. - * @parent: a pointer to the parent dentry for this file. This should be a - * directory dentry if set. If this parameter is NULL, then the - * file will be created in the root of the debugfs filesystem. - * @data: a pointer to something that the caller will want to get to later - * on. The inode.i_private pointer will point to this value on - * the open() call. - * @fops: a pointer to a struct file_operations that should be used for - * this file. - * - * This is the basic "create a file" function for debugfs. It allows for a - * wide range of flexibility in creating a file, or a directory (if you want - * to create a directory, the debugfs_create_dir() function is - * recommended to be used instead.) - * - * This function will return a pointer to a dentry if it succeeds. This - * pointer must be passed to the debugfs_remove() function when the file is - * to be removed (no automatic cleanup happens if your module is unloaded, - * you are responsible here.) If an error occurs, %NULL will be returned. - * - * If debugfs is not enabled in the kernel, the value -%ENODEV will be - * returned. - */ -struct dentry *debugfs_create_file(const char *name, umode_t mode, - struct dentry *parent, void *data, - const struct file_operations *fops) +struct dentry *debugfs_create_file_full(const char *name, umode_t mode, + struct dentry *parent, void *data, + const void *aux, + const struct file_operations *fops) { + return __debugfs_create_file(name, mode, parent, data, aux, + &debugfs_full_proxy_file_operations, + fops); +} +EXPORT_SYMBOL_GPL(debugfs_create_file_full); - return __debugfs_create_file(name, mode, parent, data, - fops ? &debugfs_full_proxy_file_operations : - &debugfs_noop_file_operations, +struct dentry *debugfs_create_file_short(const char *name, umode_t mode, + struct dentry *parent, void *data, + const void *aux, + const struct debugfs_short_fops *fops) +{ + return __debugfs_create_file(name, mode, parent, data, aux, + &debugfs_full_short_proxy_file_operations, fops); } -EXPORT_SYMBOL_GPL(debugfs_create_file); +EXPORT_SYMBOL_GPL(debugfs_create_file_short); /** * debugfs_create_file_unsafe - create a file in the debugfs filesystem @@ -422,8 +493,8 @@ EXPORT_SYMBOL_GPL(debugfs_create_file); * debugfs core. * * It is your responsibility to protect your struct file_operation - * methods against file removals by means of debugfs_use_file_start() - * and debugfs_use_file_finish(). ->open() is still protected by + * methods against file removals by means of debugfs_file_get() + * and debugfs_file_put(). ->open() is still protected by * debugfs though. * * Any struct file_operations defined by means of @@ -435,9 +506,8 @@ struct dentry *debugfs_create_file_unsafe(const char *name, umode_t mode, const struct file_operations *fops) { - return __debugfs_create_file(name, mode, parent, data, - fops ? &debugfs_open_proxy_file_operations : - &debugfs_noop_file_operations, + return __debugfs_create_file(name, mode, parent, data, NULL, + &debugfs_open_proxy_file_operations, fops); } EXPORT_SYMBOL_GPL(debugfs_create_file_unsafe); @@ -460,25 +530,16 @@ EXPORT_SYMBOL_GPL(debugfs_create_file_unsafe); * wide range of flexibility in creating a file, or a directory (if you want * to create a directory, the debugfs_create_dir() function is * recommended to be used instead.) - * - * This function will return a pointer to a dentry if it succeeds. This - * pointer must be passed to the debugfs_remove() function when the file is - * to be removed (no automatic cleanup happens if your module is unloaded, - * you are responsible here.) If an error occurs, %NULL will be returned. - * - * If debugfs is not enabled in the kernel, the value -%ENODEV will be - * returned. */ -struct dentry *debugfs_create_file_size(const char *name, umode_t mode, - struct dentry *parent, void *data, - const struct file_operations *fops, - loff_t file_size) +void debugfs_create_file_size(const char *name, umode_t mode, + struct dentry *parent, void *data, + const struct file_operations *fops, + loff_t file_size) { struct dentry *de = debugfs_create_file(name, mode, parent, data, fops); - if (de) + if (!IS_ERR(de)) d_inode(de)->i_size = file_size; - return de; } EXPORT_SYMBOL_GPL(debugfs_create_file_size); @@ -495,33 +556,42 @@ EXPORT_SYMBOL_GPL(debugfs_create_file_size); * This function will return a pointer to a dentry if it succeeds. This * pointer must be passed to the debugfs_remove() function when the file is * to be removed (no automatic cleanup happens if your module is unloaded, - * you are responsible here.) If an error occurs, %NULL will be returned. + * you are responsible here.) If an error occurs, ERR_PTR(-ERROR) will be + * returned. * * If debugfs is not enabled in the kernel, the value -%ENODEV will be * returned. + * + * NOTE: it's expected that most callers should _ignore_ the errors returned + * by this function. Other debugfs functions handle the fact that the "dentry" + * passed to them could be an error and they don't crash in that case. + * Drivers should generally work fine even if debugfs fails to init anyway. */ struct dentry *debugfs_create_dir(const char *name, struct dentry *parent) { - struct dentry *dentry = start_creating(name, parent); + struct dentry *dentry = debugfs_start_creating(name, parent); struct inode *inode; if (IS_ERR(dentry)) - return NULL; + return dentry; inode = debugfs_get_inode(dentry->d_sb); - if (unlikely(!inode)) - return failed_creating(dentry); + if (unlikely(!inode)) { + pr_err("out of free dentries, can not create directory '%s'\n", + name); + return debugfs_failed_creating(dentry); + } inode->i_mode = S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO; - inode->i_op = &simple_dir_inode_operations; + inode->i_op = &debugfs_dir_inode_operations; inode->i_fop = &simple_dir_operations; /* directory inodes start off with i_nlink == 2 (for "." entry) */ inc_nlink(inode); - d_instantiate(dentry, inode); + d_make_persistent(dentry, inode); inc_nlink(d_inode(dentry->d_parent)); fsnotify_mkdir(d_inode(dentry->d_parent), dentry); - return end_creating(dentry); + return debugfs_end_creating(dentry); } EXPORT_SYMBOL_GPL(debugfs_create_dir); @@ -541,26 +611,29 @@ struct dentry *debugfs_create_automount(const char *name, debugfs_automount_t f, void *data) { - struct dentry *dentry = start_creating(name, parent); + struct dentry *dentry = debugfs_start_creating(name, parent); struct inode *inode; if (IS_ERR(dentry)) - return NULL; + return dentry; inode = debugfs_get_inode(dentry->d_sb); - if (unlikely(!inode)) - return failed_creating(dentry); + if (unlikely(!inode)) { + pr_err("out of free dentries, can not create automount '%s'\n", + name); + return debugfs_failed_creating(dentry); + } make_empty_dir_inode(inode); inode->i_flags |= S_AUTOMOUNT; inode->i_private = data; - dentry->d_fsdata = (void *)f; + DEBUGFS_I(inode)->automount = f; /* directory inodes start off with i_nlink == 2 (for "." entry) */ inc_nlink(inode); - d_instantiate(dentry, inode); + d_make_persistent(dentry, inode); inc_nlink(d_inode(dentry->d_parent)); fsnotify_mkdir(d_inode(dentry->d_parent), dentry); - return end_creating(dentry); + return debugfs_end_creating(dentry); } EXPORT_SYMBOL(debugfs_create_automount); @@ -581,8 +654,8 @@ EXPORT_SYMBOL(debugfs_create_automount); * This function will return a pointer to a dentry if it succeeds. This * pointer must be passed to the debugfs_remove() function when the symbolic * link is to be removed (no automatic cleanup happens if your module is - * unloaded, you are responsible here.) If an error occurs, %NULL will be - * returned. + * unloaded, you are responsible here.) If an error occurs, ERR_PTR(-ERROR) + * will be returned. * * If debugfs is not enabled in the kernel, the value -%ENODEV will be * returned. @@ -594,34 +667,33 @@ struct dentry *debugfs_create_symlink(const char *name, struct dentry *parent, struct inode *inode; char *link = kstrdup(target, GFP_KERNEL); if (!link) - return NULL; + return ERR_PTR(-ENOMEM); - dentry = start_creating(name, parent); + dentry = debugfs_start_creating(name, parent); if (IS_ERR(dentry)) { kfree(link); - return NULL; + return dentry; } inode = debugfs_get_inode(dentry->d_sb); if (unlikely(!inode)) { + pr_err("out of free dentries, can not create symlink '%s'\n", + name); kfree(link); - return failed_creating(dentry); + return debugfs_failed_creating(dentry); } inode->i_mode = S_IFLNK | S_IRWXUGO; - inode->i_op = &simple_symlink_inode_operations; + inode->i_op = &debugfs_symlink_inode_operations; inode->i_link = link; - d_instantiate(dentry, inode); - return end_creating(dentry); + d_make_persistent(dentry, inode); + return debugfs_end_creating(dentry); } EXPORT_SYMBOL_GPL(debugfs_create_symlink); -static void __debugfs_remove_file(struct dentry *dentry, struct dentry *parent) +static void __debugfs_file_removed(struct dentry *dentry) { struct debugfs_fsdata *fsd; - simple_unlink(d_inode(parent), dentry); - d_delete(dentry); - /* * Paired with the closing smp_mb() implied by a successful * cmpxchg() in debugfs_file_get(): either @@ -630,66 +702,65 @@ static void __debugfs_remove_file(struct dentry *dentry, struct dentry *parent) */ smp_mb(); fsd = READ_ONCE(dentry->d_fsdata); - if ((unsigned long)fsd & DEBUGFS_FSDATA_IS_REAL_FOPS_BIT) + if (!fsd) return; - if (!refcount_dec_and_test(&fsd->active_users)) - wait_for_completion(&fsd->active_users_drained); -} -static int __debugfs_remove(struct dentry *dentry, struct dentry *parent) -{ - int ret = 0; + /* if this was the last reference, we're done */ + if (refcount_dec_and_test(&fsd->active_users)) + return; - if (simple_positive(dentry)) { - dget(dentry); - if (!d_is_reg(dentry)) { - if (d_is_dir(dentry)) - ret = simple_rmdir(d_inode(parent), dentry); - else - simple_unlink(d_inode(parent), dentry); - if (!ret) - d_delete(dentry); - } else { - __debugfs_remove_file(dentry, parent); + /* + * If there's still a reference, the code that obtained it can + * be in different states: + * - The common case of not using cancellations, or already + * after debugfs_leave_cancellation(), where we just need + * to wait for debugfs_file_put() which signals the completion; + * - inside a cancellation section, i.e. between + * debugfs_enter_cancellation() and debugfs_leave_cancellation(), + * in which case we need to trigger the ->cancel() function, + * and then wait for debugfs_file_put() just like in the + * previous case; + * - before debugfs_enter_cancellation() (but obviously after + * debugfs_file_get()), in which case we may not see the + * cancellation in the list on the first round of the loop, + * but debugfs_enter_cancellation() signals the completion + * after adding it, so this code gets woken up to call the + * ->cancel() function. + */ + while (refcount_read(&fsd->active_users)) { + struct debugfs_cancellation *c; + + /* + * Lock the cancellations. Note that the cancellations + * structs are meant to be on the stack, so we need to + * ensure we either use them here or don't touch them, + * and debugfs_leave_cancellation() will wait for this + * to be finished processing before exiting one. It may + * of course win and remove the cancellation, but then + * chances are we never even got into this bit, we only + * do if the refcount isn't zero already. + */ + mutex_lock(&fsd->cancellations_mtx); + while ((c = list_first_entry_or_null(&fsd->cancellations, + typeof(*c), list))) { + list_del_init(&c->list); + c->cancel(dentry, c->cancel_data); } - dput(dentry); + mutex_unlock(&fsd->cancellations_mtx); + + wait_for_completion(&fsd->active_users_drained); } - return ret; } -/** - * debugfs_remove - removes a file or directory from the debugfs filesystem - * @dentry: a pointer to a the dentry of the file or directory to be - * removed. If this parameter is NULL or an error value, nothing - * will be done. - * - * This function removes a file or directory in debugfs that was previously - * created with a call to another debugfs function (like - * debugfs_create_file() or variants thereof.) - * - * This function is required to be called in order for the file to be - * removed, no automatic cleanup of files will happen when a module is - * removed, you are responsible here. - */ -void debugfs_remove(struct dentry *dentry) +static void remove_one(struct dentry *victim) { - struct dentry *parent; - int ret; - - if (IS_ERR_OR_NULL(dentry)) - return; - - parent = dentry->d_parent; - inode_lock(d_inode(parent)); - ret = __debugfs_remove(dentry, parent); - inode_unlock(d_inode(parent)); - if (!ret) - simple_release_fs(&debugfs_mount, &debugfs_mount_count); + if (d_is_reg(victim)) + __debugfs_file_removed(victim); + simple_release_fs(&debugfs_mount, &debugfs_mount_count); } -EXPORT_SYMBOL_GPL(debugfs_remove); /** - * debugfs_remove_recursive - recursively removes a directory + * debugfs_remove - recursively removes a directory * @dentry: a pointer to a the dentry of the directory to be removed. If this * parameter is NULL or an error value, nothing will be done. * @@ -701,128 +772,100 @@ EXPORT_SYMBOL_GPL(debugfs_remove); * removed, no automatic cleanup of files will happen when a module is * removed, you are responsible here. */ -void debugfs_remove_recursive(struct dentry *dentry) +void debugfs_remove(struct dentry *dentry) { - struct dentry *child, *parent; - if (IS_ERR_OR_NULL(dentry)) return; - parent = dentry; - down: - inode_lock(d_inode(parent)); - loop: - /* - * The parent->d_subdirs is protected by the d_lock. Outside that - * lock, the child can be unlinked and set to be freed which can - * use the d_u.d_child as the rcu head and corrupt this list. - */ - spin_lock(&parent->d_lock); - list_for_each_entry(child, &parent->d_subdirs, d_child) { - if (!simple_positive(child)) - continue; - - /* perhaps simple_empty(child) makes more sense */ - if (!list_empty(&child->d_subdirs)) { - spin_unlock(&parent->d_lock); - inode_unlock(d_inode(parent)); - parent = child; - goto down; - } - - spin_unlock(&parent->d_lock); - - if (!__debugfs_remove(child, parent)) - simple_release_fs(&debugfs_mount, &debugfs_mount_count); - - /* - * The parent->d_lock protects agaist child from unlinking - * from d_subdirs. When releasing the parent->d_lock we can - * no longer trust that the next pointer is valid. - * Restart the loop. We'll skip this one with the - * simple_positive() check. - */ - goto loop; - } - spin_unlock(&parent->d_lock); + simple_pin_fs(&debug_fs_type, &debugfs_mount, &debugfs_mount_count); + simple_recursive_removal(dentry, remove_one); + simple_release_fs(&debugfs_mount, &debugfs_mount_count); +} +EXPORT_SYMBOL_GPL(debugfs_remove); - inode_unlock(d_inode(parent)); - child = parent; - parent = parent->d_parent; - inode_lock(d_inode(parent)); +/** + * debugfs_lookup_and_remove - lookup a directory or file and recursively remove it + * @name: a pointer to a string containing the name of the item to look up. + * @parent: a pointer to the parent dentry of the item. + * + * This is the equlivant of doing something like + * debugfs_remove(debugfs_lookup(..)) but with the proper reference counting + * handled for the directory being looked up. + */ +void debugfs_lookup_and_remove(const char *name, struct dentry *parent) +{ + struct dentry *dentry; - if (child != dentry) - /* go up */ - goto loop; + dentry = debugfs_lookup(name, parent); + if (!dentry) + return; - if (!__debugfs_remove(child, parent)) - simple_release_fs(&debugfs_mount, &debugfs_mount_count); - inode_unlock(d_inode(parent)); + debugfs_remove(dentry); + dput(dentry); } -EXPORT_SYMBOL_GPL(debugfs_remove_recursive); +EXPORT_SYMBOL_GPL(debugfs_lookup_and_remove); /** - * debugfs_rename - rename a file/directory in the debugfs filesystem - * @old_dir: a pointer to the parent dentry for the renamed object. This - * should be a directory dentry. - * @old_dentry: dentry of an object to be renamed. - * @new_dir: a pointer to the parent dentry where the object should be - * moved. This should be a directory dentry. - * @new_name: a pointer to a string containing the target name. + * debugfs_change_name - rename a file/directory in the debugfs filesystem + * @dentry: dentry of an object to be renamed. + * @fmt: format for new name * * This function renames a file/directory in debugfs. The target must not * exist for rename to succeed. * - * This function will return a pointer to old_dentry (which is updated to - * reflect renaming) if it succeeds. If an error occurs, %NULL will be - * returned. + * This function will return 0 on success and -E... on failure. * * If debugfs is not enabled in the kernel, the value -%ENODEV will be * returned. */ -struct dentry *debugfs_rename(struct dentry *old_dir, struct dentry *old_dentry, - struct dentry *new_dir, const char *new_name) +int __printf(2, 3) debugfs_change_name(struct dentry *dentry, const char *fmt, ...) { - int error; - struct dentry *dentry = NULL, *trap; + int error = 0; + const char *new_name; struct name_snapshot old_name; + struct dentry *target; + struct renamedata rd = {}; + struct inode *dir; + va_list ap; - trap = lock_rename(new_dir, old_dir); - /* Source or destination directories don't exist? */ - if (d_really_is_negative(old_dir) || d_really_is_negative(new_dir)) - goto exit; - /* Source does not exist, cyclic rename, or mountpoint? */ - if (d_really_is_negative(old_dentry) || old_dentry == trap || - d_mountpoint(old_dentry)) - goto exit; - dentry = lookup_one_len(new_name, new_dir, strlen(new_name)); - /* Lookup failed, cyclic rename or target exists? */ - if (IS_ERR(dentry) || dentry == trap || d_really_is_positive(dentry)) - goto exit; - - take_dentry_name_snapshot(&old_name, old_dentry); - - error = simple_rename(d_inode(old_dir), old_dentry, d_inode(new_dir), - dentry, 0); + if (IS_ERR_OR_NULL(dentry)) + return 0; + + va_start(ap, fmt); + new_name = kvasprintf_const(GFP_KERNEL, fmt, ap); + va_end(ap); + if (!new_name) + return -ENOMEM; + + rd.old_parent = dget_parent(dentry); + rd.new_parent = rd.old_parent; + rd.flags = RENAME_NOREPLACE; + target = lookup_noperm_unlocked(&QSTR(new_name), rd.new_parent); + if (IS_ERR(target)) + return PTR_ERR(target); + + error = start_renaming_two_dentries(&rd, dentry, target); if (error) { - release_dentry_name_snapshot(&old_name); - goto exit; + if (error == -EEXIST && target == dentry) + /* it isn't an error to rename a thing to itself */ + error = 0; + goto out; } - d_move(old_dentry, dentry); - fsnotify_move(d_inode(old_dir), d_inode(new_dir), old_name.name, - d_is_dir(old_dentry), - NULL, old_dentry); + + dir = d_inode(rd.old_parent); + take_dentry_name_snapshot(&old_name, dentry); + simple_rename_timestamp(dir, dentry, dir, rd.new_dentry); + d_move(dentry, rd.new_dentry); + fsnotify_move(dir, dir, &old_name.name, d_is_dir(dentry), NULL, dentry); release_dentry_name_snapshot(&old_name); - unlock_rename(new_dir, old_dir); - dput(dentry); - return old_dentry; -exit: - if (dentry && !IS_ERR(dentry)) - dput(dentry); - unlock_rename(new_dir, old_dir); - return NULL; + end_renaming(&rd); +out: + dput(rd.old_parent); + dput(target); + kfree_const(new_name); + return error; } -EXPORT_SYMBOL_GPL(debugfs_rename); +EXPORT_SYMBOL_GPL(debugfs_change_name); /** * debugfs_initialized - Tells whether debugfs has been registered @@ -833,21 +876,51 @@ bool debugfs_initialized(void) } EXPORT_SYMBOL_GPL(debugfs_initialized); +static int __init debugfs_kernel(char *str) +{ + if (str) { + if (!strcmp(str, "on")) + debugfs_enabled = true; + else if (!strcmp(str, "off")) + debugfs_enabled = false; + else if (!strcmp(str, "no-mount")) { + pr_notice("debugfs=no-mount is a deprecated alias " + "for debugfs=off\n"); + debugfs_enabled = false; + } + } + + return 0; +} +early_param("debugfs", debugfs_kernel); + static int __init debugfs_init(void) { int retval; + if (!debugfs_enabled) + return -EPERM; + retval = sysfs_create_mount_point(kernel_kobj, "debug"); if (retval) return retval; - retval = register_filesystem(&debug_fs_type); - if (retval) + debugfs_inode_cachep = kmem_cache_create("debugfs_inode_cache", + sizeof(struct debugfs_inode_info), 0, + SLAB_RECLAIM_ACCOUNT | SLAB_ACCOUNT, + init_once); + if (debugfs_inode_cachep == NULL) { sysfs_remove_mount_point(kernel_kobj, "debug"); - else - debugfs_registered = true; + return -ENOMEM; + } - return retval; + retval = register_filesystem(&debug_fs_type); + if (retval) { // Really not going to happen + sysfs_remove_mount_point(kernel_kobj, "debug"); + kmem_cache_destroy(debugfs_inode_cachep); + return retval; + } + debugfs_registered = true; + return 0; } core_initcall(debugfs_init); - diff --git a/fs/debugfs/internal.h b/fs/debugfs/internal.h index f0d73d86cc1a..c95699b27a56 100644 --- a/fs/debugfs/internal.h +++ b/fs/debugfs/internal.h @@ -1,4 +1,4 @@ -// SPDX-License-Identifier: GPL-2.0 +/* SPDX-License-Identifier: GPL-2.0 */ /* * internal.h - declarations internal to debugfs * @@ -7,26 +7,52 @@ #ifndef _DEBUGFS_INTERNAL_H_ #define _DEBUGFS_INTERNAL_H_ +#include <linux/list.h> struct file_operations; +struct debugfs_inode_info { + struct inode vfs_inode; + union { + const void *raw; + const struct file_operations *real_fops; + const struct debugfs_short_fops *short_fops; + debugfs_automount_t automount; + }; + void *aux; +}; + +static inline struct debugfs_inode_info *DEBUGFS_I(struct inode *inode) +{ + return container_of(inode, struct debugfs_inode_info, vfs_inode); +} + /* declared over in file.c */ extern const struct file_operations debugfs_noop_file_operations; extern const struct file_operations debugfs_open_proxy_file_operations; extern const struct file_operations debugfs_full_proxy_file_operations; +extern const struct file_operations debugfs_full_short_proxy_file_operations; struct debugfs_fsdata { const struct file_operations *real_fops; - refcount_t active_users; - struct completion active_users_drained; + const struct debugfs_short_fops *short_fops; + struct { + refcount_t active_users; + struct completion active_users_drained; + + /* protect cancellations */ + struct mutex cancellations_mtx; + struct list_head cancellations; + unsigned int methods; + }; }; -/* - * A dentry's ->d_fsdata either points to the real fops or to a - * dynamically allocated debugfs_fsdata instance. - * In order to distinguish between these two cases, a real fops - * pointer gets its lowest bit set. - */ -#define DEBUGFS_FSDATA_IS_REAL_FOPS_BIT BIT(0) +enum { + HAS_READ = 1, + HAS_WRITE = 2, + HAS_LSEEK = 4, + HAS_POLL = 8, + HAS_IOCTL = 16 +}; #endif /* _DEBUGFS_INTERNAL_H_ */ |